Year	% of expense
2003	19.219444250498533
2004	25.49610848543041
2005	26.69690620995464
2006	26.351486168144895
2007	26.329489612222062
2008	24.628969437939045
2009	21.895086383724077
2010	24.192487333897418
2011	28.75256092539507
2012	25.394676138612905
2013	24.457741797789925
2014	25.87476791403115
2015	24.703130161990437
2016	28.290937888283562
2017	28.2719254099012
2018	27.386915085376945
2019	26.88736978450575
2020	29.041459775793406
2021	28.46030729702809